Wireless telemetry systems use a wireless (e.g., radio frequency) communications network to allow the measurement of information by remote devices and the transmission of the measured to a central monitoring station (CMS). Typical wireless telemetry systems also enable the control of remote device through the counter part of telemetry, telecommand.
In general, telemetry systems are employed for the purpose of monitoring environmental conditions or equipment parameters. Such systems are employed in a wide variety of applications including security, health monitoring, vehicle and asset tracking, and device and equipment monitoring and control.
A typical telemetry system includes a number of remote measuring devices, an encoder for encoding the measurements as analog or digital communication signals, and a transmission means for transmitting the communication signals.
Some telemetry systems use a wireless telecommunications system to transmit the telemetry application data. To effect such a system, the mobile equipment of the telecommunication system is controlled by a telemetry application. Typically the telemetry application is programmed into firmware of the mobile equipment.
Telemetry applications provide the ability for a telemetry device to obtain measurement data at remote location and transmit the data over a wireless network to a central monitoring station. Such applications are considered machine-to-machine applications as no human user is involved. That is, for such applications, the data is input from a machine connected to the mobile station and not from a human user of the mobile station.
An exemplary telemetry application providing a method for communicating telemetry application data (TAD) over a control channel of a wireless communication network is described in U.S. Pat. No. 5,845,203 to Ladue ('203 Patent). As described in the '203 Patent, TAD from a remote device is encoded in a stream of dialed digits along with a remote feature control request (RFCR). The telemetry application described in the '203 Patent exploits the RFCR to transmit TAD from the remote device to the CMS. The remote device is assigned a Mobile Identification Number (MIN) so that it appears as a roaming cell phone to a local MSC. The local MSC then, acts as the serving MSC for remote device. The area code specified in the assigned MIN is selected so that the CMS functions as the HLR associated with the home MSC for the remote device. The CMS further appears as a service control point (SCP) on the SS7 network to receive the RFCR and TAD automatically forwarded by the serving MSC.
This is effected as follows. An RFCR is placed in the dialed digits stream accompanying a call origination message initiated by the wireless communicator. Additionally, TAD is also placed in the dialed digits stream. The call origination message and dialed digits stream is transmitted over a control channel to the serving MSC. The serving MSC receives the call origination message and associated dialed digits stream, and detects the RFCR, triggering the serving MSC to forward the dialed digits stream, including the RFCR and the application specific data, over the SS7 network, to the CMS/SCP on the SS7 network.
As evident from this example, telemetry applications may be quite sophisticated which results in a substantial disadvantage. As note above the telemetry application may be programmed in firmware in the mobile equipment. This means that providers of telemetry applications have to approach mobile equipment manufacturers independently to have the telemetry application implemented within each type of mobile equipment. Therefore such a scheme is time-consuming and costly. Moreover, this may contribute to inconsistencies in the telemetry applications between mobile equipment manufacturers.